Fuel injectors



Nov. 20, 1956 G. ALRIC FUEL INJECTORS Filed Sept. 24, 1954 M m g H m mm A N M 5 U a M United States Patent FUEL INJECTORS Gustave Alric, Sainte-Savine, France Application September 24, 1954, Serial No. 458,036

Claims priority, application France September 26, 1952 7 Claims. (Cl. 299.107.6)

The present invention relates to volumetric fuel injectors for feeding fuel to internal combustion engines, the term volumetric injector including all injection apparatus having at least one variable volume chamber (called pressure chamber) into which there is periodically fed a predetermined quantity of liquid which operates movable means serving to control the feed of fuel to at least one injection orifice.

My invention is more especially, but not exclusively, concerned with apparatus of this kind in which liquidtightness of the pressure chamber is obtained by means of at least one resilient tubular elementbearing at one end upon a surface rigid with the body of the apparatus and at its other end upon a surface rigid with said movable means.

The chief object of my invention is to provide an apparatus of this kind which is better adapted to meet the requirements of practice and in particular when the movable means are subjected to holding stresses tending to brake the normal displacements thereof.

In the apparatus with which my invention is concerned, the pressure chamber is arranged to be placed in communication with the injection orifice through a delivery passage controlled by a main valve member operative by said movable means so as to be periodically opened in response to pressure rises produced in said chamber by the forcing thereinto of successive amounts of fuel. My fuel injector is characterized by the interposition, between the outlet of said delivery passage and said injection orifice, of at least one auxiliary valve member arranged to be forced into opening position by said pressure rises and urged toward closing position by resilient means of a force lower than that exerted on said valve member by said periodical pressure rises, whereby every periodical pressure rise in said pressure chamber, after starting the opening of said main valve means, produces, in said passage between said main valve means and said auxiliary valve member, a counter-pressure which achieves first a sharp opening of said main valve means and, thereafter, a sharp opening of said auxiliary valve member.

According to another feature of my invention, andespecially When the means for achieving liquid-tightness of the pressure chamber include .a resilient tubular element interposed between faces respectively rigid with the body of the apparatus and with the above mentioned movable .means, said means being rigid with the main valve member, the portion of said main valve member which cooperates with said passage in order to control it is given a spherical shape cooperating with a conical valveseat rigid with .one end of said passage, so as to obtain a linear contact (along a circular circle of the sphere) between said main valve member and its seat, even when the movable means are slightly out of line due to a loose guiding thereof whichis admissible in this kind of apparatus.

Preferred embodiments of my invention will be hereinafter described with reference to the accompanying Patented Nov. 20, 1956 drawings, given merely by way of example and in which: Fig. 1 is an axial sectional view of a fuel injector made according to a first embodiment of my invention.

Figs. 2 and 3 are part views showing modifications of the construction of Fig. 1.

The apparatus according to my invention, as illustrated by Fig. 1, includes at least one pressure chamber A periodically fed with fuel under pressure, for instance through a volumetric pump (not shown) connected with said pressure chamber A through a conduit I. Said pressure chamber A can be placed in communication with one or several injection orifices proper 2 through a passage 3 controlled by movable means 4 operated (in' the opening direction) by pressure rises produced in pressure chamber A by the injection of fuel into said chamber by the injection pump.

Preferably, and as it will be more fully explained hereinafter, this system is arranged in such manner that liquidtightness of pressure chamber A is achieved by means of at least one elastic member 5 (and preferably by a plurality of such members piled upon one another) interposed between bearing surfaces 6 and 7 respectively rigid with the body C of the apparatus and movable means 4. Owing to such an arrangement, which is particularly simple, it is possible to machine the guiding means of movable member 4 with only a low precision.

Movable means 4 are provided at their inner end with a main valve member 8 adapted to cooperate with valve seat means formed at the end of passage 3 which is adjacent to chamber 8.

.It should be noted that, for the sake of clarity of Fig l, the relative dimensions of the lower portion of the ail Paratus, and especially of valve member 8 and its seat, of passage 3 and of injection orifices 2, have been enlarged.

Now, according to my invention, I interpose between passage 3 and injection orifices 2 at least one auxiliary valve system essentially constituted by a valve member 9 urged toward its closing position by resilient means (for instance a spring 10) of a force lower than that exerted on said valve member 9 by the pressure rises periodically produced in pressure chamber A. Advantageously, the force of spring 10 is about one half of that of the force produced by said pressure rises.

Advantageously, as shown by the drawing, auxiliary valve member 9 is in the form of a check valve preferably having a flat bearing surface and housed together with-spring 10 in a chamber 11 extending from the outlet end of passage 3 to injection orifices 2. v i

This injection apparatus operates as follows:

When the injection pump produces in pressure chamber A a periodical pressure rise, this pressure rise starts upward movement of movable member 4 whereby valve member 8 is lifted off its seat. As soon as said memher is detached from its seat, the pressure existing in chamber A is transmitted into the space existing between valve member 8 and auxiliary valve member 9 thus causing valve member s to lift sharply from its seat, after which, as soon as the pressure existing in chamber A is transmitted to the space existing between valve merriber 8 and valve member 9, said last mentioned member 9 is also moved away from its seat, whereby the pressure existing in chamber A opens sharply valve member 9 the spring 19 of which is, as above stated, of a strength lower than the pressure forces exerted on member 9. Fuel can then pass through passage 3 and chamber 11 on its way to injection orifices 2 through which it is introduced in the form of atomized jets into the combustion chamber to be fed with fuel. As soon as this outflow of fuel has sufficiently reduced the pressure in pressure chamber A, the springs again become preponderating over the pressure forces and the valve members close down, i. e. are applied upon their valve seats. The whole is then ready for a further pressure rise exerted in chamber A.

From this description of the operation, it is clear that between two successive injections, the pressure must drop to a low value in passage 3. Therefore it is not desirable to have valve member 9 tightly applied upon its seat. The shape of this value member 9 (fiat shape) shown in the drawings is therefore quite well adapted for the desired result and i may even provide in valve 9 or in its seat a slight groove so as to obtain the desired pressure drop in passage 3 once valve member 8 is closed. Of course, the leakage thus obtained must be sufiiciently low to permit the creation of the counter-pressure which sharply moves valve member 9 away from its seat.

Experience teaches that it is possible thus to obtain, due to this double control of the fuel flow toward the injection orifices 2, a sharp limitation of injection, that is to say to avoid any transitory periods as exist in the known apparatus at the beginning and at the end of injection.

Figs. 1 to 3 show advantageous embodiments of injectors according to my invention.

According to the first embodiment, illustrated by Fig. 1, chamber 11 communicates directly with the injection orifices 2.

According to the second embodiment, illustrated by Fig. 2, the injection orifices Z are controlled by a slide valve 12 rigidly connected with valve member 9, said slide valve 12 being arranged so as gradually to open the injection orifices 2 during the opening of valve member 9.

According to the third embodiment, illustrated by Fig. 3, there is only one injection orifice 2 of general annular shape, and preferably frusto-conical as shown by the drawing, a flat head 13 acting as a deflector to obtain a radial distribution of the circular sheet injected through annular orifice 2.

Advantageously, according to another feature of my invention, the valve member 8 is given the shape of a portion of a sphere and the seat upon which this valve member is applied is of frusto-conical shape.

In this way I always obtain, when the valve member 8 is bearing upon its seat, a linear contact, that is to say a contact along a circle of the sphere, between the valve member and its seat. Such a contact is always obtained despite slight variations of direction of the stem 4 of the valve member, which variations are likely to occur in view of the relatively loose mounting of stem 4 in its guiding means.

Thus, since a contact is always obtained, liquid-tightness is fully ensured. But, on the other hand, due to the fact that this contact is linear, there is avoided any risk of wiredrawing the liquid when the valve member is being lifted and the pressure rise in chamber A is immediately transmitted without pressure drop to the active area of valve member 9. The injector according to my invention is very simple in construction and reliable in its operation and its upkeep requires no special precautions.

In a general manner, while I have, in the above description, disclosed what I deem to be practical and efiicient embodiments of my invention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

What I claim is:

l. A fuel injector which comprises, in combination, rigid casing means shaped to form a pressure chamber adapted to be fed periodically with successive quantities of fuel, a discharge chamber provided with at least one injection orifice, and a passage between said two chambers, whereby fuel flows first through said pressure chamber, then through said passage and finally through said discharge chamber to said injection orifice, means movable in said pressure chamber to make the volume thereof variable, valve seat means forming the end of said passage adjacent to said pressure chamber, a main valve member connected with said movable means located in said pressure chamber and arranged to cooperate with said valve seat means to open said end of said passage when said movable means are moved to increase the volume of said pressure chamber, resilient means for urging said valve member toward said valve seat means, said valve and said valve seat being shaped to cause a predetermined pressure rise in said pressure chamber to lift said valve member away from said valve seat means, i. e. toward the inside of said pressure chamber, against the action of said resilient means, valve seat means forming the other end of said passage adjacent to said discharge chamber, an auxiliary valve member in said discharge chamber mounted to cooperate with said second mentioned valve seat means to control the communication between said passage and said injection orifice, and resilient means for urging said auxiliary valve member toward said second mentioned valve seat means, the force of said last mentioned resilient means being lower than the force exerted on said auxiliary valve member by the pressure existing in said passage after the opening of said main valve member by said predetermined pressure rise in said pressure chamber.

2. A fuel injector which comprises, in combination, rigid casing means shaped to form a pressure chamber adapted to be fed periodically with successive quantities of fuel, a discharge chamber provided with at least one injection orifice, and a passage between said two chambers, whereby fuel flows first through said pressure chamber, then through said passage and finally through said discharge chamber tosaid injection orifice, means movable in said pressure chamber to make the volume thereof variable, said means extending to the outside of said pressure chamber, said means and said chamber being provided with surfaces facing each other and located inside said pressure chamber, a tubular'packing member having its ends applied against said surfaces to keep said chamber liquid-tight, valve seat means forming the end of said passage adjacent to said pressure chamber, a main valve member connected with said movable means located in said pressure chamber and arranged to cooperate with said valve seat means to open said end of said passage when said movable means are moved to increase the volume of said pressure chamber, resilient means for urging said valve member toward said valve seat means, said valve and said valve seat being shaped to cause a predetermined pressure rise in said pressure chamber to lift said valve member away from said valve seat means, i. e. toward the inside of said pressure chamber, against the action of said resilient means, valve seat means forming the other end of said passage adjacent to said discharge chamber, an auxiliary valve member in said discharge chamber mounted to cooperate with said second mentioned valve seat means to control the communication between said passage and said injection orifice, and resilient means for urging said auxiliary valve member toward said second mentioned valve seat means, the force of said last mentioned resilient means being lower than the force exerted'on said auxiliary valve member by the pressure existing in said passage after the opening of said main valve member by said predetermined pressure rise in said pressure chamber.

3. A fuel injector according to claim 2 in which said main valve member is in the form of a portion of a sphere and is carried by the inner end of said movable means, the valve seat means cooperating with said sphereshaped valve member being of frusto-conical shape.

4. A fuel injector which comprises, in combination, rigid casing means shaped to form a pressure chamber adapted to be fed periodically with successive quantities of fuel, a discharge chamber provided with at least one injection orifice, and a passage between said two chambers, whereby fuel flows first through said pressure chamber,

then through said passage and finally through said discharge chamber to said injection orifice, means movable in said pressure chamber to make the volume thereof variable, valve seat means forming the end of said passage adjacent to said pressure chamber, a main valve member connected with said movable means located in said pressure chamber and arranged to cooperate with said valve seat means to open said end of said passage when said movable means are moved to increase the volume of said pressure chamber, resilient means for urging said valve member toward said valve seat means, said valve and said valve seat being shaped to cause a predetermined pressure rise in said pressure chamber to lift said valve member away from said valve seat means, i. e. toward the inside of said pressure chamber, against the action of said resilient means, valve sea means forming the other end of said passage adjacent to said discharge chamber, an auxiliary valve member in said discharge chamber mounted to cooperate with said second mentioned valve seat means to control the communication between said passage and said injection orifice, the respective cooperating surfaces of said auxiliary valve member and its valve seat means being flat, and resilient means for urging said auxiliary valve member toward said second mentioned valve seat means, the force of said last mentioned resilient means being lower than the force exerted on said auxiliary valve member by the pressure existing in said passage after the opening of said main valve member by said predetermined pressure rise in said pressure chamber.

5. A fuel injector according to claim 1 in which said discharge chamber which contains the auxiliary valve member communicates directly with the injection orifices.

6. A fuel injector according to claim 1 further including a slide valve rigidly connected with the auxiliary slide member, said slide valve being arranged so as gradually to open the injection orifices during the opening of said auxiliary valve member.

7. A fuel injector according to claim 1 which comprises a single injection orifice of general annular shape, said orifice being preferably of frusto-conical form and a flat head opposite said orifice acting as a deflector to radially distribute the circular sheet injected through said annular ormce.

References Cited in the file of this patent UNITED STATES PATENTS 2,035,264 Edwards Mar. 24, 1936 FOREIGN PATENTS 579,211 Germany June 27, 1933 900,977 France Oct. 23, 1944 

